The Effect of Core and Epitendinous Suture Modifications on Repair of Intrasynovial Flexor Tendons in an In Vivo Canine Model

Abstract

Purpose To determine in-vivo effects of modifications to core and epitendinous suture techniques in a canine intrasynovial flexor tendon repair model using clinically relevant rehabilitation. Our null hypothesis was that gap formation and rupture rates would remain consistent across repair techniques. Methods We evaluated gap formation and rupture in 75 adult mongrel dogs that underwent repair of intrasynovial flexor tendon lacerations followed by standardized post-operative therapy. The current suture technique was a 4-0, 8-strand core suture with a purchase of 1.2 cm and a 5-0, epitendinous suture repair with a 2 mm purchase length and depth. Gap and failure were compared by chi-squared analysis to a historical group of in-vivo repairs (n=76) from the same canine model using 8-strand core suture repair with purchase of 0.75 cm and 6-0 epitendinous suture with a 1 mm purchase length and depth. Results Ninety-three percent of tendons (n = 70) demonstrated gapping of <3 mm using the current suture technique. Five percent of tendons (n = 4) had a gap of 3 mm or greater, and there was 1 repair site failure. This was significantly improved over the comparison group of historical 8-strand core repair technique which resulted in 82% (n = 62) and 81% (n=112) of repairs with a gap of <3 mm and 7 failures (9%). Conclusions In an in-vivo model, current modifications of suture techniques for intrasynovial flexor tendon repair demonstrated significant improvements in gap formation and rupture compared to a similar technique using shorter purchase lengths and shallower purchase depth. Clinical Relevance Suggested repair modifications for the treatment of Zone 2 flexor tendon transections demonstrate improvements in gap formation and tendon rupture in-vivo.

The Effect of Suture Caliber and Number of Core Suture Strands on Zone II Flexor Tendon Repair: A Study in Human Cadavers

“…Further, suture repair techniques incorporating locked stitches, preloading of the core suture(10), and over-tensioning the core suture across the repair site(11) have been associated with improved tensile properties in repaired tendons. While many of the commonly used flexor tendon repair techniques appear to provide sufficient time zero tensile strength for the initiation of passive motion rehabilitation, enhancement of the mechanical properties of flexor tendon repair has been related to decreased risk of gap formation and repair failure (2–4, 6, 11, 12). …”

“…Superior values for time zero, ex vivo tensile properties in flexor tendon repair have been observed when a nonabsorbable 4-0 double-stranded (looped) suture is used to perform an 8-strand core suture repair method that employs a deep, 1.2-cm core suture purchase depth and a deep, 2-mm epitendinous suture purchase(12, 13). Although similar results were obtained in a recent in vivo study using a large animal model(12) , many surgeons prefer 4-strand repair techniques, presumably due to their familiarity and ease.…”

The role of animal models in tendon research

“…99 In the past, the canine model was relied upon to perform research on flexor tendons. 98-100 More recently, a wider variety of animals have been used to characterise flexor tendon injury and repair, including chicken, 101 canine, 102-104 ovine, 105 porcine, 106,107 and rabbit 105-110 models. The best choice of model system will depend on the essential characteristics that must be mimicked for a particular research question.…”

Cell and Biologic-Based Treatment of Flexor Tendon Injuries

“…12 Major repair technique advances by Kessler, 9 then Pennington, 10 and then Winters and Gelberman 4 have changed Zone II intrasynovial flexor digitorum profundus (FDP) tendon treatment from an inoperable “no man’s land” 8 to a common surgical procedure. Following several decades of repair 3,4,9,10,13–22 and rehabilitation 23–25 improvements, we have reached a plateau in Zone II flexor tendon repair outcomes with current methods. Clincial outcomes remain highly variable, necessitating alternative approaches.…”